Sensex has recorded the fastest 10,000-point rally to reach the 80,000 mark for the first time on Wednesday. The benchmark index crossed the 70,000 mark on December 11 last year and took less than 140 sessions to hit 80,000, Moneycontrol reported. Sensex took 166 sessions from 50,000 to 60,000 and 548 sessions to reach 70,000.